Files
hermes-agent/tools/environments/ssh.py

156 lines
5.7 KiB
Python

"""SSH remote execution environment with ControlMaster connection persistence."""
import logging
import subprocess
import tempfile
import threading
import time
from pathlib import Path
from tools.environments.base import BaseEnvironment
from tools.interrupt import is_interrupted
logger = logging.getLogger(__name__)
class SSHEnvironment(BaseEnvironment):
"""Run commands on a remote machine over SSH.
Uses SSH ControlMaster for connection persistence so subsequent
commands are fast. Security benefit: the agent cannot modify its
own code since execution happens on a separate machine.
Foreground commands are interruptible: the local ssh process is killed
and a remote kill is attempted over the ControlMaster socket.
"""
def __init__(self, host: str, user: str, cwd: str = "~",
timeout: int = 60, port: int = 22, key_path: str = ""):
super().__init__(cwd=cwd, timeout=timeout)
self.host = host
self.user = user
self.port = port
self.key_path = key_path
self.control_dir = Path(tempfile.gettempdir()) / "hermes-ssh"
self.control_dir.mkdir(parents=True, exist_ok=True)
self.control_socket = self.control_dir / f"{user}@{host}:{port}.sock"
self._establish_connection()
def _build_ssh_command(self, extra_args: list = None) -> list:
cmd = ["ssh"]
cmd.extend(["-o", f"ControlPath={self.control_socket}"])
cmd.extend(["-o", "ControlMaster=auto"])
cmd.extend(["-o", "ControlPersist=300"])
cmd.extend(["-o", "BatchMode=yes"])
cmd.extend(["-o", "StrictHostKeyChecking=accept-new"])
cmd.extend(["-o", "ConnectTimeout=10"])
if self.port != 22:
cmd.extend(["-p", str(self.port)])
if self.key_path:
cmd.extend(["-i", self.key_path])
if extra_args:
cmd.extend(extra_args)
cmd.append(f"{self.user}@{self.host}")
return cmd
def _establish_connection(self):
cmd = self._build_ssh_command()
cmd.append("echo 'SSH connection established'")
try:
result = subprocess.run(cmd, capture_output=True, text=True, timeout=15)
if result.returncode != 0:
error_msg = result.stderr.strip() or result.stdout.strip()
raise RuntimeError(f"SSH connection failed: {error_msg}")
except subprocess.TimeoutExpired:
raise RuntimeError(f"SSH connection to {self.user}@{self.host} timed out")
def execute(self, command: str, cwd: str = "", *,
timeout: int | None = None,
stdin_data: str | None = None) -> dict:
work_dir = cwd or self.cwd
exec_command, sudo_stdin = self._prepare_command(command)
wrapped = f'cd {work_dir} && {exec_command}'
effective_timeout = timeout or self.timeout
# Merge sudo password (if any) with caller-supplied stdin_data.
if sudo_stdin is not None and stdin_data is not None:
effective_stdin = sudo_stdin + stdin_data
elif sudo_stdin is not None:
effective_stdin = sudo_stdin
else:
effective_stdin = stdin_data
cmd = self._build_ssh_command()
cmd.extend(["bash", "-c", wrapped])
try:
kwargs = self._build_run_kwargs(timeout, effective_stdin)
# Remove timeout from kwargs -- we handle it in the poll loop
kwargs.pop("timeout", None)
_output_chunks = []
proc = subprocess.Popen(
cmd,
stdout=subprocess.PIPE,
stderr=subprocess.STDOUT,
stdin=subprocess.PIPE if effective_stdin else subprocess.DEVNULL,
text=True,
)
if effective_stdin:
try:
proc.stdin.write(effective_stdin)
proc.stdin.close()
except Exception:
pass
def _drain():
try:
for line in proc.stdout:
_output_chunks.append(line)
except Exception:
pass
reader = threading.Thread(target=_drain, daemon=True)
reader.start()
deadline = time.monotonic() + effective_timeout
while proc.poll() is None:
if is_interrupted():
proc.terminate()
try:
proc.wait(timeout=1)
except subprocess.TimeoutExpired:
proc.kill()
reader.join(timeout=2)
return {
"output": "".join(_output_chunks) + "\n[Command interrupted]",
"returncode": 130,
}
if time.monotonic() > deadline:
proc.kill()
reader.join(timeout=2)
return self._timeout_result(effective_timeout)
time.sleep(0.2)
reader.join(timeout=5)
return {"output": "".join(_output_chunks), "returncode": proc.returncode}
except Exception as e:
return {"output": f"SSH execution error: {str(e)}", "returncode": 1}
def cleanup(self):
if self.control_socket.exists():
try:
cmd = ["ssh", "-o", f"ControlPath={self.control_socket}",
"-O", "exit", f"{self.user}@{self.host}"]
subprocess.run(cmd, capture_output=True, timeout=5)
except (OSError, subprocess.SubprocessError):
pass
try:
self.control_socket.unlink()
except OSError:
pass